<template>
    <div class="app-container">
        <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="最终发布"/>
    </el-steps>

   <el-form label-width="120px">

   <el-form-item label="课程标题">
    <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"/>
     </el-form-item>

      <!-- 所属分类 TODO -->
       <el-form-item label="课程分类">
         <el-select
             v-model="courseInfo.subjectParentId"
             placeholder="一级分类" @change="subjectLevelOneChanged">

              <el-option
               v-for="subject in subjectOneList"
               :key="subject.id"
               :label="subject.title"
               :value="subject.id"/>
         </el-select>

              <!--二级分类 -->
            <el-select
             v-model="courseInfo.subjectId"
             placeholder="二级分类">

              <el-option
               v-for="subject in subjectTwoList"
               :key="subject.id"
               :label="subject.title"
               :value="subject.id"/>

              </el-select>
         </el-form-item>

       <!-- 课程讲师 -->
        <el-form-item label="课程讲师">
         <el-select
             v-model="courseInfo.teacherId"
             placeholder="请选择">

              <el-option
               v-for="teacher in teacherList"
               :key="teacher.id"
               :label="teacher.name"
               :value="teacher.id"/>

              </el-select>
         </el-form-item>

    <el-form-item label="总课时">
      <el-input-number :min="0" v-model="courseInfo.lessonNum" controls-position="right" placeholder="请填写课程的总课时数"/> 
     </el-form-item>

  <!-- 课程简介 TODO -->
      <el-form-item label="课程简介">
         <tinymce :height="300" v-model="courseInfo.description"/>
      </el-form-item>

         <!-- 课程封面 TODO -->
        <el-form-item label="课程封面">
         <el-upload
           :show-file-list="false"
           :on-success="handleAvatarSuccess"
           :before-upload="beforeAvatarUpload"
           :action="BASE_API+'/eduoss/fileoss'"
           class="avatar-uploader">
           <img :src="courseInfo.cover">
         </el-upload>
        </el-form-item>


  <el-form-item label="课程价格">
     <el-input-number :min="0" v-model="courseInfo.price" controls-position="right" placeholder="免费课程请设置为0元"/> 元
   </el-form-item>

   <el-form-item>
     <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
   </el-form-item>
  </el-form>
 </div>
</template>
<script>
import course from '@/api/edu/course'
import subject from '@/api/edu/subject'
import Tinymce from '@/components/Tinymce'//引入组件
export default {
    //声明组件
    components: { Tinymce },
    data(){
        return{
            saveBtnDisabled: false,
            courseInfo:{
                title:'',
                subjectId:'',//二级分类id
                subjectParentId:'',//一级分类id
                teacherId:'',
                lessonNum:0,
                description:'',
                cover:'/static/7.jpg',
                price:0
            },
            BASE_API: process.env.BASE_API,//接口API地址
            teacherList:[],//封装所有的讲师
            subjectOneList:[],//一级分类
            subjectTwoList:[]//二级分类
        }
    },
    created(){
        //初始化所有讲师
        this.getListTeacher()
        //初始化一级分类
        this.getOneSubject()
    },
    methods:{
        //上传封面成功调用的方法
        handleAvatarSuccess(res, file){
           this.courseInfo.cover = res.data.url
        },
        //上传之前调用的方法
        beforeAvatarUpload(file){
            const isJPG = file.type === 'image/jpeg'
            const isLt2M = file.size / 1024 / 1024 < 2
            if (!isJPG) {
            this.$message.error('上传头像图片只能是 JPG 格式!')
            }
            if (!isLt2M) {
            this.$message.error('上传头像图片大小不能超过 2MB!')
            }
            return isJPG && isLt2M

        },
        //点击某个一级分类，触发change，显示对应二级分类
        subjectLevelOneChanged(value){
            //value就是一级分类id值
            //遍历所有的分类，包含一级和二级
            for(var i=0; i<this.subjectOneList.length;i++){
                //每个一级分类
                var oneSubject = this.subjectOneList[i]
                //判断：所有一级分类id 和 点击一级分类id是否一样
                if(value === oneSubject.id){
                    //从一级分类获取里面所有的二级分类
                    this.subjectTwoList = oneSubject.children
                    //把二级分类id值清空
                    this.courseInfo.subjectId = ''
                }
            }
        },
        //查询所有的一级分类
        getOneSubject(){
            subject.getSubjectList()
                .then(response =>{
                    this.subjectOneList = response.data.list
                })
        },
        //查询所有的讲师
        getListTeacher(){
            course.getListTeacher()
                 .then(response => {
                     this.teacherList = response.data.items
                 })
        },
        saveOrUpdate(){
            course.addCourseInfo(this.courseInfo)
                .then(response => {
                    //提示
                     this.$message({
                     type: 'success',
                     message: '添加课程信息成功!'
                });
                //跳转到第二步
                this.$router.push({path:'/course/chapter/'+response.data.courseId})
             })
        }
    }    
}
</script>
<style scoped>
.tinymce-container {
  line-height: 29px;
}
</style>